Switch



April 14, 1942. R- KNQpp 2,279,753

SWITCH Filed March 25, 1940 El L Wam:

Patented Apr. 14, 1942 UNITED sTATEs PATENT OFFICE (Cl. 20o-4) Claims.

My present invention .relates to a switch `particularly adapted for heating pads and the like, where the switch is.` mounted ina current supply cord and controls selectively a plurality of heating elements or other electrically operated the circuit through the switch prior to disengagement of any of the slidable circuit closing elements from each other.

A further object is to provide a switch structure which can be inexpensively manufactured of a minimum of parts and readily assembled without the necessity of complicated wiring connections and parts alignment prior to enclosing of the switch mechanism in a two-part casing provided therefor.

Still another. object is to provide a switch structure in which a. simple sliding circuit closing element cooperates slidably with stationary circuit closing elements and arcingbetween the elements is prevented by the use of a single circuit breaker having' separable contacts operated by the movable circuit closing element, and which may be made of tungsten, platinum or the like, thus confining all arcing to the one pair kof contacts.

A further object is to provide means to impart more or less snap action to the contacts of the circuit breaker to aid in minimizing arcing between them When the circuit is broken.

With these and othery objects in View, my invention consists lin the. construction, arrangement and combination of the various parts of my device whereby the objects contemplated are attained, as hereinafter more vfully set forth, pointed out in my claims and illustrated in the accompanying drawing, wherein:

Figure 1 is a plan view of my switch structure with the upper casing member removed and the screws for holding itin position shown in section;

Figure 2 is a longitudinal sectional view on the line 2-2 of Figure 1, showing the upper part of the casing in position; l

Figure 3 is a similar transverse sectional View on the line 3-3 of Figure 1;

Figure 4 is a separated perspective view of a slidable member and a movable circuit closing element of my switch structure, and

Figures 5, 6, 'l and 8 are diagrammatic views showing the switch .adjusted for, respectively,- low heat, medium heat, high heat and just prior to olf, the off position being shown in Figure 1.

On the accompanying drawing I have used the reference character C to indicate a casing comprised of a lower portion I0 and an upper portion I2. The portions I0 and I2 are held together by four screws I3.

Within the lower portion I0 of the casing C, I provide a. movable platelike member I4 formed preferably of insulating material and having a plurality of upstanding projections I5, I6, Il' and I8 and a downwardly directed projection I9. The member I4 is adapted to slide on the bottom of the casing portion IU with the element I9 projected through a slot 20 therein for the purpose of guiding the member I4 in its sliding movement and toform a protuberance that can be engaged by the thumb or finger of the user for sliding the member I4 to its various positions.

Resting on the platelike member I4 is another plate 2l of current-conducting material notched out to iit the projections I5, I6, Il and I8. The plate 2| has projections 22, 23 and. 24 extending between the projections of the plate l4and slightly beyond the edge thereof, as shown in Figure l, to serve as movable circuit-closing contacts. Opposite the contacts 22, 23 and 24 is a series of notches 25, 26, 2'I and 28.

For cooperation with the movable contacts 22, 23 and 24, I provide a pair of stationary circuit-closing elements or contacts 29 and 30. The contacts 29 and 30 are in the form of leaf springs of suitable shape fitting in sockets 3l and 32 of the lower portion lll of the casing C and held therein by a. partition wall 33 preferably of insulation. The wall 33 is held in its proper position by projections 34 from the upper portion I2 of the casing C when the two portions of the casing are assembled and the screws I3 inserted in position.

In connection with my switch structure, I provide a circuit breaker comprising leaf springs 35 and 36 carrying contacts 3'I and 38 and an operator for the circuit breaker comprising another leaf spring 39. The leaf spring 39 has a cam portion 40 to cooperate with the various notches 25, 26, 21 and 28 and terminates in a finger 4I for operating the circuit breaker, as will hereinafter appear. .The springs 35 and 39 are spot welded together at their left end in Figure 1 and fit in a socket 42 of the lower casing portion I0 for assembly purposes. Similarly, the spring 36 ts in a socket 43.

A pair of current supply wires 44 and 45 are provided which pass through a retainer washer 46 held in grooves 41 and 48 of one end of the casing C. The supply wire 45 passes on through another retainer washer 49 held in grooves 59 and 5l of the casing portions iD and I2.

The supply wire 45 is connected with one end of a low heat heating element L and with one end of a medium heat heating element M, as shown diagrammatically. The other end of the heating element L is connected by a wire 52 to the stationary contact 30 and the other end of the heating element M is connected by a wire 53 to the stationary contact 29. The wire 44 is connected to the circuit breaker spring 36.

Practical operation 29-53 and M back to 45.

When the switch is adjusted for high heat, as in Figure '7, then current flows as follows: 44- 35-38--31-35-39-40-25 and 2l, after which it divides, part going through 23-30-52 and L to 45, and part going through 22-29-53 and M to 45. In this instance both the low and medium heating elements L and M are energized, thus giving high heat.

In Figure 8, the plates i4 and 2i are being moved from low to oi position, the cam 4B leaving the notch 21 prior to entering the notch 28 as the plates are moved in the direction of the arrow a. It will be noted that in this intermediate position between notches, the cam 45 has been lifted to bend the spring 35 upwardly to open the contacts 31 and 38 of the circuit breaker. The movable contact 24 has not yet disengaged the stationary contact 30 and it is therefore evident that the circuit has been broken through the circuit breaker so that it does not have to be broken across the sliding contacts 24 and 3i). A little further movement of the plates I4 and 2l toward the left will result in the switch being in oi position.

The notches 25, 25, 21 and 28 are all so related with respect to the contacts 22, 23 and 24 that the circuit breaker will be opened similarly as described in connection with Figure 8 just prior to disengagement of any of these three contacts from the contacts 29 and 38. rIlhus the only possible arcing that can occur lis across the circuit breaker contacts 31 and 38 and these may be made of tungsten or platinum without great expense, since there are only two of them, thus conning all circuit opening operations to these two contacts only. Making them of tungsten or platinum results in the provision of contacts which will usually give lifetime service, and ii cleaning is required it would be only after many years use of the switch. Also, by the use of the notch and cam arrangement, some snap action is imparted to the contacts 31 and 33 of the circuit breaker, whereas only relatively slow sliding movement occurs between the movable contacts 22, 23 and 24 and the stationary contacts 29 and 39. The result is a satisfactory straight line operating switch for heating pads and the like, which can be inexpensively manufactured and will give trouble-free service.

For low heat in Figure 5, the

While I have shown a particular embodiment of my invention, it will be understood of course that I do not wish to be limited thereto since many modifications may be made, and I therefore contemplate by the claims appended hereto to cover any such modications or substitutions of mechanical equivalents as fall within the true spirit and scope of my invention without sacricing any of its advantages.

I claim as new and desire to secure by Letters Patent of the United States:

1. In a switch structure, a two-part casing, a slidable member in one part of said casing, a loose partition member between said parts of said casing, means in said other part to retain said partition member in position for confining said slidable member to a predetermined sliding position in said one part of said casing, a plurality of stationary circuit closing elements in said casing, a movable circuit closing element cooperating with said stationary circuit closing elements and carried by said slidable member, and circuit breaking means operated by movement of said slidable member to break the circuit through said switch prior to disengagement of said movable circuit closing element from any one of said stationary circuit closing elements.

2. In a switch structure, two hollowed out parts arranged with their concave sides facing each other to form a casing, a slidable member in one of said parts, a partition member between said parts and held by the other part for conning said slidablemember to a. predetermined sliding position in said one of said parts, a plurality of stationary circuit closing elements in said casing, a movable circuit closing element cooperating with said stationary circuit closing elements and carried by said slidable member, and a circuit breaker operated by movement of said slidable member to break the circuit through said switch prior to any disengagement o1" said movable circuit closing element from said stationary circuit closing elements.

3. In a switch structure, a casing, a slidable plate of insulating material therein, an operating knob on said insulating plate, said casing having a slot through which said knob extends to the exterior of the casing, projections on one face of said insulating plate opposite said knob, a circuit closing plate on said insulating plate and having notches to receive said projections, a plurality of stationary circuit closing elements engageable and disengageable with relation to said projections and the edge of said circuit closing plate between said projections, said circuit closing plate having a series of V notches in its other edge, a circuit breaker, and an operating element for said circuit breaker having a cam portion cooperating with said V notches to open said circuit breaker prior to disengagement of said circuit closing plate from any one of said stationary circuit closing elements.

4. In a switch structure, a casing, a slidable plate of insulating material therein, an operating knob on said insulating plate, said casing having a slot through which said knob extends to the exterior of the casing, projections on one face of said insulating plate opposite said knob, a circuit closing plate on said insulating plate and having notches to receive said projections, a plurality of stationary circuit closing elements engageable and disengageable with relation to said projections and the edge of said circuit closing plate between said projections, a. circuit breakerl including a pair of contacts normally engaged for opposite edge of said plate, said circuit breaker comprising a leaf spring detent, said plate having a series of notches to receive said detent with snap action and a pair of contacts, one of which is carried by a leaf spring engaged by said detent when not in one of said notches to break the circuit of said stationary circuit closing elements prior to disengagement of said one edge of said plate from any one of said stationary circuit closing elements as the plate is moved 1ongitudinally of said casing.

RUDOLPH KNOPP. 

